Device for maintaining and changing the pressure in tires

ABSTRACT

A device for maintaining and changing the pressure in a is provided whereby the inner pressure space of the tire is connected through a pump to a pressure accumulator which, at its input and/or output into the inner pressure space of the tire, is fitted with at least one pressure control element. The pump can be a peristaltic pump in the shape of a deformable hose placed on the perimeter of the tire, fitted with an air inlet and an air outlet, while the air inlet and the air outlet are positioned on the perimeter of the tire distant from each other by a preset length, dependent on the deformation of the tire.

BACKGROUND AND SUMMARY

The present application is a continuation of U.S. application Ser. No.15/659,990, filed Jul. 26, 2017, which is a continuation of U.S.application Ser. No. 14/359,868, filed May 21, 2014, (now U.S. Pat. No.9,744,815, issued Aug. 29, 2017, which was the U.S. national stage ofInternational Application PCT/CZ2012/000114, filed Nov. 13, 2012, andwhich claimed priority to Czech Application PV 2011-757, filed Nov. 22,2011, all of which are incorporated by reference.

This invention concerns a device for maintaining and changing thepressure in tires.

There are different methods for re-inflating a tire when using anintegrated pump that is driven by the tire deformation, the rotation ofthe wheel, by using an electronic device or by pressure changes in thetyre, etc. All of these systems are used for compensating forunder-inflation by re-inflating the tire with ambient air to thepressure specified by the tire manufacturer. Any excess of air may thenbe released from the tire. This solution requires the purification ofthe air and communication between the interior and exterior of the tirethat might cause contamination. Re-inflation through the exterior of thetire is a relatively lengthy process, however. In the case of a valvefailure the tire can become completely deflated, which creates adangerous condition. The purpose of the device described below is toreduce or to avoid the need for tire inflation by using ambient air.

Based on this invention, the drawbacks described above have, to a largeextent, been eliminated by the device for maintaining and changing thepressure in tires. Its operational principle is based on a pump thatinterconnects the interior of the tire with an accumulator that issupplied with at least one pressure control element at its inlet and/oroutlet to the interior of the tire.

The pressure accumulator can either be connected to the tire and/or tothe inner tube and/or the rim and/or it can constitute an integral partof the tyre, the inner tube, or the rim. This, in effect, has theadvantage that the pressure accumulator is fitted with an additionalinlet for ambient air or with an air outlet to the exterior of the tire.Based on this advantageous design, the pump is connected at one end tothe interior space of the tire and/or with the exterior of the tireand/or the accumulator and at the other end it is connected with theinterior of the tire and/or the exterior of the tire and/or theaccumulator.

The principle that this invention also represents is as a device formaintaining and changing the pressure in tires when the pump is aperistaltic pump in the form of a deformable hose positioned on theperimeter of the tyre, i.e. anywhere on tire both including tread andsidewall, inside the tire wall, or on the tire wall or near the tirewall from outside or inside of the tire. The hose is fitted with both anair inlet and outlet, while these are placed apart from each other onthe tire perimeter, separated at a preset length, in accordance with thedeformation of the tire.

The pump is provided with at least one valve. This means that there willbe a section with a minimum volume capacity at the inlet and/or outletof the pump. The pump can be fitted with a valve, i.e. a three-wayvalve, with inputs for a pump source and a pump target and while oneinput is fitted to the valve, the second is connected to the pump andthe last input is connected to the closure fixture.

A ring is attached to the inner side of the pump and the distance of itsouter edge from the axis of the tire rotation is equal to between a 1 to1.1 multiple of the distance of the bottom side of the pump from theaxis of the tire rotation. The pump has the form of a curved hollowchannel with at least one of its outer walls partially formed by thesections of two planes that lie in the same longitudinal direction asthe pump, forming an angle of α=0 to 120°, while if α>0°, it is locatedat the contact edge of these two planes, situated on the far side fromthe centre of the cross-section of the pump.

The principle of the invention also represents a tire and/or rim and/orinner tube containing an adhesive and/or a profile lock forinterconnection with any element from the group of the tire and/or rimand/or inner tube and/or pump.

Additionally, the principle of the invention is a tire and/or rim and/orinner tube and/or pump, modified for the placement of any device, inaccordance with the above described requirements.

Another principle of the invention is the above described device whichconstitutes a part of the tyre, inner tube, and/or rim.

A major advantage is that, compared to the familiar system wherebypressure is adjusted by releasing air externally or by refilling withair from outside, this device does not need to be re-inflated with airfrom outside, thereby avoiding contamination, possible corrosion, andtire failure. Following a drop in the pressure the air is refilled fromoutside and in the case of excess pressure the air is released to theexterior. Frequently the tires are cold-inflated to a certain pressurelevel and then, after reaching the presumed temperature, the pressureadjusts to the previously estimated level which, in principle, is acompromise pressure that has been calculated theoretically for theentire nexus—the specific type of tyre, the vehicle, the environment,etc. Therefore the tire doesn't reach the pressure level required inoperation until it has warmed-up and even when it is warmed-up thepressure, at best, is close to its ideal status only in a random numberof the targeted tires. Based on our model the tyre-accumulator systemmay simply be overinflated, while the pressure inside the tire isactually ideal, regardless of the temperature and the other operatingconditions. It remains true that in our model this can be achievedwithout any exchange of air with the external environment and evenwithout the need for a valve when the system consists of only a simplepump and an accumulator. The built-in accumulator can ensure a rapidchange of pressure when, for example, prior to the vehicle movingthrough a curve the air from the accumulator is transferred to theselected tyre, which alters its tread contact, and the air issubsequently returned to the accumulator. Or vice versa—in a racing car,for example, the tires rapidly become overinflated on the straights andtherefore the tire has minimal resistance and it then deflates andreaches the ideal level of tread contact in the bends.

The peristaltic pump design described here is also simplified to theutmost and a simple hose of the appropriate length can achieve there-inflation or the deflation of the tire to the pressure that providesthe required tread contact. This simplicity of operation increases thereliability of the device, while at the same time reducing its cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The device for maintaining and changing the pressure in will bedescribed in more detail using particular design examples from theattached drawings, in which

FIGS. 1a to 1e show the specific design elements of the pressureaccumulator schematically.

FIGS. 2a to 2i show the hose-shaped chamber inside the tireschematically and

FIGS. 3a to 3c show the connection to the chamber inside the tire.

DETAILED DESCRIPTION Example 1

FIG. 1 shows schematically the pressure accumulator Z, interconnectedwith the interior space of the tire P. The hollow of the tire isinterconnected with the accumulator Z through the pump K. In thisexample, the cold tire P has a pressure of 2 atm. and the accumulator Zalso has a pressure of 2 atm. While driving, the tire P warms up and thetotal pressure in the tire P increases to 2.3 atm. At the same time, apart of the air volume is being moved by the pump K, represented by abroken-line arrow, into the accumulator Z. The pressure in the rest ofthe tire P therefore remains at the level of 2 atm. In this example, thepressure in the accumulator Z has increased up to 2.6 atm. This statusis shown in FIG. 1 a.

Example 2

When the tire P becomes cooler or following leakage of air from the tireP, the air from the accumulator Z returns to the tire P through thepreset valve RV and it maintains its desired pressure level. This isshown in FIG. 1, in which the pressure control valve RV passes the airfrom the accumulator Z in the direction of the grey arrow, the tire Phas a pressure of 2 atm. and the accumulator Z has a pressure of lessthan the original 2.6 atm.

In practice, the pump K can continuously pump air into the accumulator Zwhile, concurrently, the valve RV can be releasing air back to the tireP, as is shown in FIG. 1c , in which the tire P has a pressure of 2 atm.and the accumulator Z has the same or a higher pressure. In this mannerthe air is circulated by the pump K from the tire P into the accumulatorZ and back, which means that the pump K can be run continuously. Thepressure control valve RV can be replaced by a simple opening with asuitable profile and throughput or even by a return valve or anothervalve, while the air from the accumulator Z can return to the tire Pdirectly through the pump K, or the accumulator Z can be freelyinterconnected with the tire P. With an assembly such as this, when thepump K is pumping, the pressure in the accumulator Z is also increasing,and when it is not pumping, the pressure in the accumulator Z isdecreasing and the pressure in the tire P is increasing until they areequal or until the pump K restarts. The control element RV, whether itis a valve, the pump K or another element, can be placed in front of orbehind the pump K or, alternatively, it can be placed in front of orbehind the accumulator Z. Air can also be directed from the pump K intothe accumulator Z only if the tire P is overinflated; then the air canbe moved by the pump K only from the tire P or into the tire P andtherefore the output of the pump K is directed to the accumulator Z onlyas necessary, or the input of the pump K from the tire P can be closed.

The tire P can also be significantly overinflated during its first use,in comparison with the required value, and during the first ride anyexcessive air will then be pumped into the accumulator Z, where it willbe retained until the time of its further use for compensating againstleaks or against cold.

The air can be stored in the accumulator Z or drawn back from it even ina situation in which there is a change in the operating conditions, suchas the driving style, the vehicle load or a weather change that alsorequires a change to the pressure of the tire P. The accumulator Z mayalso be overinflated during the first mounting of the tire P andsubsequently the air can be pumped between the accumulator Z and thetire P or even from/to the outside by use of the pump K. One or morepumps K can thereby re-inflate the tires P either from outside O or fromthe accumulator Z or, in turn, draw the air from outside O or from thetire P into the accumulator Z. The accumulator Z can be situateddirectly in the pressure space or the inner tube of the tire P oroutside them.

When the pressure in the tire P and the accumulator Z is lower than thatrequired and it is effective to draw it from outside O or from the tireP then the pump K can be used to re-inflate the tire P or theaccumulator Z from outside O. It may also be effective to use the pump Kto pump the air from the accumulator Z into the tire P; in this case,for example, the pump K could re-inflate the tire P despite the factthat this would create negative pressure in the accumulator Z.

The pump K can thereby be interconnected with multiple-directionalvalves on either its input and/or its output, which would then directthe air from the outside O, the accumulator Z, or the tire P to theoutside O, to the accumulator Z, or to the tire P as needed.

These options are delineated in FIG. 1d , in which the pump K has 3sources at its input as well as at its output and is distributing airbetween them in different variants as shown in FIG. 1 e.

Example 3

The length of the tread contact of the tire P can be used forcontrolling the pressure in the tire P. For example, the peristalticpump uses hose cross deformation for its functioning; this deformationmoves longitudinally through the hose and pushes the compressed ortransported medium forward. Thereby the peristaltic pump located in thetire wall or close to it can make use of the lengthwise motion of thetire deformation for its functioning when loaded.

The length of the tire tread deformation corresponds to the inflation ofthe tire. This means that if the deformation length becomes too greatthe tire will be underinflated and if the deformation length is tooshort the tire will be overinflated. If a tire with a pressure of 3 atm.is interconnected, using the peristaltic pump, with the outsideenvironment of the tire that has a pressure of 1 atm. and the pump isdesigned in such a manner that when rolling forward it moves the airtowards the tyre, while, at the same time, this design does not includeany valves, the following options are possible:

The tire rolls forward and air from outside moves through theperistaltic pump chamber into the tire as it is rolling and moving thedeformation through the chamber. However, if the deformation disappearsfrom the chamber through the output opening, while, at the same time, nodeformation has yet occurred at the chamber input opening, then thechamber connects the tire with the outside and air can flow freelyoutside the tire until the chamber is compressed at a certain point andis disconnected by the deformation. The leakage of the air can beterminated by another deformation of the tire during a new rotation oralso by the increase of the tread contact of the deflated tire andthereby also increasing the length of the deformation; this deformationwill gradually reach as far as the input or output of the chamber andwill disconnect it.

The peristaltic pump can be designed in such a manner that before thedeformation leaves from one end of the chamber, the deformation willclose the chamber at the other end. The air from the tire thereby cannotpass further back into the chamber than to this deformation point, whichwill then force the air back into the tire. The volume of air that hasbeen drawn into the chamber will thereby be sealed off at its end fromits source by the new deformation, prior to the disappearance of theoriginal deformation at its head that connects this volume with the tireinner space and forces it into the tire. In such a case, the volume ofnew air that was closed in the chamber, between its parts closed by thedeformation, will get into the tire. The volume defined in this manneris transported and forced into the tire.

FIG. 2a shows the pump K in the shape of the tubular chamber encompassedby the tire casing. The input VST into the chamber is drawing the airfrom outside O into the chamber and, at the same time, the chambercontents are forced out into the tire through its output VYS. In thisexample the chamber is not fitted with any valves. FIGS. 2b and 2c showthe partial rotation of the tire in the direction of the arrow and themovement of the air from outside into the chamber, represented by thearrow at the input VST and simultaneously from the chamber into thetyre, as shown by the arrow at the output VYS. In FIG. 2d the chamberreaches the position in which it is not loaded with any deformation andthe chamber freely interconnects the inside of the tire with the outsideand the air from the tire is able to flow out freely.

This figure already shows a tread contact in the form of a greyrectangle with the points indicating where the last chamber-treadcontact is situated. These points are represented as small circles.

The direction of the air flow arrows has changed. The air from the tireis moved into the chamber under pressure and from the chamber it isemerging into the outside environment.

FIG. 2e shows the leak continuing until the tire turns into the positionshown in FIG. 2f , at which point the chamber will be disconnected bythe tire deformation and subsequently air will move into the tire bybeing drawn in from outside where the status is reaching the positionshown in FIG. 2a and is going round and round. The volume of the leakedair depends on the length of time during which the chamber has not beenloaded with the deformation, i.e. the length of the tire perimeter,without the chamber deformation, and the rotation rate.

The same situation exists in the example shown in FIG. 2g as that inFIG. 2e , except that the tire rotation has ceased, which is depicted bythe crossed rotation arrow above the picture. The air flows out of thetire freely through the opening VYS into the chamber and out of it againthrough the opening VST. The air leakage results in a broader treadcontact. After a certain time the situation returns to the status shownin FIG. 2h , whereby the chamber is disconnected by the deformation andno air is flowing out through the chamber. The length of the treadcontact has thereby stopped the air leak.

In this manner it is possible to design a system through which, bysetting the chamber length, it is possible to ensure that the tire willbe re-inflated only when the tread contact length is greater than thedesired length and at the same time it is possible to ensure thatsubsequently the re-inflation is completed. Additionally, the tire caneven be deflated if the tread contact is too short, until the rightlength has been reached. A higher inflation pressure value desired at agreater speed can also be ensured.

In practice, a valve can be added to this system to prevent leakage, forexample, in situations in which the entire wheel is of the ground or forreasons of adjustment. At the same time a non-deformable part of thechamber can be included into the system. Before it starts to draw in theair through the valve, the chamber must pump out the air from itsnon-deformable part and only after its evacuation will the valve beopened and start re-inflating steadily. This works in a similar mannereven when the non-deformable part is placed in front of the valve if itis separating the chamber from the target area. The chamber then needs,for example, two full rotations to evacuate the air from thisineffective capacity and only after that will it start moving the airregularly from the source and/or to the target.

Example 4

The main purpose of the pump is to re-pump the air into the area ofhigher pressure. Examples 1 and 2 describe the accumulator being placedinside the tyre; Example 3 then describes a chamber that can be set upin such a manner that it only pumps when the tread contact is longerthan the desired value.

If one pump is moving the air from the tire P into the accumulator Z andthen the accumulator Z is deflating the air into the intermediateaccumulator MZ so that this intermediate accumulator has a consistentlylower pressure than that of the tire P, then the pump described inExample 3 can re-pump the air from this intermediate accumulator MZ intothe tire P only if the tread contact is longer than the desired value.Similarly, if the tread contact is shorter than the desired value, aircan be drawn off from the tire P into the accumulator Z.

In FIG. 3a there is an underinflated tire P=2.5 atm., which is connectedto the accumulator Z with the pressure of 5 atm. by the pump K1; the airfrom the accumulator Z passes through the valve RV into the intermediateaccumulator MZ where a constant pressure of 2 atm. is being maintainedby the valve RV. As the tread contact of the tire P is longer thanrequired, the pump K2 is pumping air from the intermediate accumulatorMZ into the tire P. After the tread contact of the tire P becomesshorter, which in this case occurs under a pressure of 3 atm., the pumpK2 ceases pumping and the system will enter into the state shown in FIG.3b . The tire P has a pressure of 3 atm., the accumulator Z has apressure of 4.8 atm. and the intermediate accumulator MZ has a pressureof 2 atm.

If the pump K2 has a higher delivery rate than does pump K1, thesituation can arise, for example, in which the tire P becomes punctured,whereby all the air from both the accumulator Z and the intermediateaccumulator MZ will be moved into tire P through the pump K2 and anegative pressure against the outer atmosphere will occur there. If thespace of the accumulator Z or of the intermediate accumulator MZ isinterconnected with another air source, in this case with the outside Oof the tire P, it will start to draw in air from it. This is shown inFIG. 3c , in which the intermediate accumulator MZ is drawing in airthrough the valve JV. If a small leak is being compensated the wholesystem can be re-inflated in this manner up to the values shown in FIG.3 a.

INDUSTRIAL UTILITY

The device for maintaining and changing the pressure in tyres, accordingto this technical solution, will find use especially for passenger andcommercial vehicles.

1. A device for maintaining pressure in a tire, comprising: a firstaccumulator; a second accumulator; a first pump arranged to interconnectan inner pressure space of the tire and the first accumulator, a valvearranged to interconnect the first accumulator and the secondaccumulator, a second pump arranged to interconnect the secondaccumulator and the inner pressure space of the tire.
 2. The device ofclaim 1, wherein the first pump comprises a chamber having deformablewalls at least partially defining the chamber, the walls having shapememory.
 3. The device of claim 1, wherein the second pump comprises achamber having deformable walls at least partially defining the chamber,the walls having shape memory.
 4. The device of claim 1, wherein thevalve comprises a check valve.
 5. The device of claim 1, wherein thesecond accumulator is interconnected with a second valve, and the secondvalve connected to the environment.
 6. The device of claim 1, whereinthe first pump comprises a peristaltic pump including a deformable hosepositioned on a perimeter of the tire.
 7. The device of claim 1, whereinthe second pump comprises a peristaltic pump including a deformable hosepositioned on a perimeter of the tire.
 8. The device of claim 3, whereinthe tire is deformed over the length of deformation when the tire isinflated to a pressure within a design pressure range and subjected to athreshold load.
 9. The device of claim 8, wherein the length of thechamber is less than or equal to the length of deformation.
 10. A devicefor maintaining pressure in a tire, comprising: a first accumulator; asecond accumulator; an inner pressure space of the tire in fluidcommunication with the first accumulator through a first pump; the firstaccumulator being in fluid communication with the second accumulatorthrough a valve, the second accumulator being in fluid communicationwith the inner pressure space of the tire through a second pump.
 11. Thedevice of claim 10, wherein the first pump comprises a chamber havingdeformable walls at least partially defining the chamber, the wallshaving shape memory.
 12. The device of claim 10, wherein the second pumpcomprises a chamber having deformable walls at least partially definingthe chamber, the walls having shape memory.
 13. The device of claim 10,wherein the valve comprises a check valve.
 14. The device of claim 10,wherein the second accumulator is in fluid communication with theenvironment through a second valve.
 15. The device of claim 10, whereinthe first pump comprises a peristaltic pump including a deformable hosepositioned on a perimeter of the tire.
 16. The device of claim 10,wherein the second pump comprises a peristaltic pump including adeformable hose positioned on a perimeter of the tire.
 17. The device ofclaim 12, wherein the tire is deformed over the length of deformationwhen the tire is inflated to a pressure within a design pressure rangeand subjected to a threshold load.
 18. The device of claim 17, whereinthe length of the chamber is less than or equal to the length ofdeformation.